Traditionally, antenna beam-steering has been accomplished using mechanical positioners, multiple beam antennas, and active phased-arrays. Mechanical positioners have been used to direct a single antenna in the desired direction. The mechanical positioner is essentially a robot that moves the antenna in the azimuth (left, right) and elevation (up, down) directions to achieve the desired antenna position. Mechanical positioners are not preferred due to maintenance requirements, speed limitations, and the reliability of the rotary joints.
Multiple-beam antennas use multiple separate antennas pointed in different directions and switch between the separate antennas. Since the use of a large number of individual antennas is not practical, lower gain antennas are traditionally used to cover a wider area. The gain for multiple-beam antennas is further reduced at beam cross-over points. For some applications, the reduction of gain for multiple-beam antennas excludes them as a viable option.
Phased-arrays include a large number of antenna elements (e.g., transmit/receive (T/R) modules) arranged in a plane. For millimeter-wave frequencies (above 30 GHz), phased-arrays are expensive because hundreds or thousands of antenna elements are required and the spacing becomes a difficult and expensive constraint to meet because the wavelengths are small.
For the reasons stated above and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the specification, there is a need in the art for improved systems and methods for two-dimensional antenna beam-steering at millimeter-wave frequencies.